An electrodeposited inhomogeneous metal–insulator–semiconductor junction for efficient photoelectrochemical water oxidation

Abstract

The photoelectrochemical splitting of water into hydrogen and oxygen requires a semiconductor to absorb light and generate electron-hole pairs, and a catalyst to enhance the kinetics of electron transfer between the semiconductor and solution. A crucial question is how this catalyst affects the band bending in the semiconductor, and, therefore, the photovoltage of the cell. We introduce a simple and inexpensive electrodeposition method to produce an efficient n-Si/SiOx/Co/CoOOH photoanode for the photoelectrochemical oxidation of water to oxygen. The photoanode functions as a solid-state, metal-insulator-semiconductor photovoltaic cell with spatially non-uniform barrier heights in series with a low overpotential water-splitting electrochemical cell. The barrier height is a function of the Co coverage; it increases from 0.74 eV for a thick, continuous film to 0.91 eV for a thin, inhomogeneous film that has not reached coalescence. The larger barrier height leads to a 360 mV photovoltage enhancement relative to a solid-state Schottky barrier.

Light‐Induced Activation of Adaptive Junction for Efficient Solar‐Driven Oxygen Evolution: In Situ Unraveling the Interfacial Metal–Silicon Junction

“…These Ni 0 atoms could diffuse toward the Si surface, and thus the silicide phase (i.e., NiSi) could be generated following the electroless reduction of Ni cations. [9,18,21] The present results revealed that this photoinduced adaptive layer can significantly increase the band bending near the silicon/metal/electrolyte interface and thereby induce a higher barrier height, thereby leading to the enhancement of photovoltage. Guided by all these findings, we propose that the formation of this adaptive phase concurs with the transformation of nickel metal into nickel oxides/oxyhydroxides and the presence of exposed silicon oxide on the electrolyte/electrode interface, as displayed in the schematic for photoinduced water oxidation on n-Si@Ni (Figure 8a).…”

“…[10,15] In some cases, by employing a physical/chemical deposition technique, such as atomic layer deposition (ALD), [16,17] metal oxide or metallic layers with precisely controlled thicknesses have been demonstrated to be highly efficient/durable systems for solar-driven water splitting; however, these techniques are limited for practical applications with large-scale and low-cost requirements. [18,21] Notably, this enhancement of the effective barrier height of the electrodeposited photoanodes strongly depends on the environment of the inhomogeneous metal/semiconductor junction, and the adventitious growth of silicon oxide [22] on the photoanode may generate either an adaptive or a dense junction that results in different photovoltaic properties during the photoinduced reactions. [18,21] Notably, this enhancement of the effective barrier height of the electrodeposited photoanodes strongly depends on the environment of the inhomogeneous metal/semiconductor junction, and the adventitious growth of silicon oxide [22] on the photoanode may generate either an adaptive or a dense junction that results in different photovoltaic properties during the photoinduced reactions.…”

Recent Advances and Emerging Trends in Photo‐Electrochemical Solar Energy Conversion

“…[99] Moreover, the Co/CoOOH catalyst was deposited by a low energy intensity electrodeposition technique, an inexpensive method that results in a large increase in efficiency. [99] Moreover, the Co/CoOOH catalyst was deposited by a low energy intensity electrodeposition technique, an inexpensive method that results in a large increase in efficiency.…”

Electrodeposition of Gold on Lignocelluloses and Graphite-Based Composite Paper Electrodes for Superior Electrical Properties

“…30,31 EDT is of low cost with ease in production without requirements of heavy instruments, high vacuum, and high-temperature conditions. 32 Electrodeposition is widely used to generate conductive layers/surfaces due to charge transfer processes. Electrodeposition of gold on substrates is a common way to increase the electronically conductive characteristics.. [33][34][35][36] The reasons to use gold for electrodeposition for superior conductive properties of paper-based graphite electrodes are: (i) relatively higher electrical conductivity among family of metals (ii) large oxidizing potential window iii) an economical way to produce nanostructures without the requirement of a reduced environment.…”

“…Electrodeposition of gold on substrates is a common way to increase the electronically conductive characteristics.. [33][34][35][36] The reasons to use gold for electrodeposition for superior conductive properties of paper-based graphite electrodes are: (i) relatively higher electrical conductivity among family of metals (ii) large oxidizing potential window iii) an economical way to produce nanostructures without the requirement of a reduced environment. 32 This study presents the fabrication of lignocelluloses/graphite composite sheets to address the flexibility of graphite as an electrode and further electrodeposition of gold to enhance the electrical properties for energy storage applications. According to our literature survey this work is the first attempt of electrodeposition on lignocelluloses/graphite composite sheets, which will open the possibilities to use graphite for bulk level applications of energy storage devices and disposable electronics.…”